This invention relates to a process for gluing an automobile windshield into its bay or opening by simultaneously extruding through a nozzle an adhesive mass in bead form and a flexible high tensile wire. The bead acts immediately as a glue or, after hardening, as a bead of interlayer between the glazing and another bead of glue. The wire is used for the shearing of the adhesive bead during a possible later removal of the glazing.
In a known installation method, the bead of glue is deposited on the edge of the glazing and a flexible wire is placed either in the core of the bead or in its immediate vicinity (European patent application No. EP 0 121 480). In this known process, to remove the glazing from the vehicle, the flexible wire must cut across the entire width of the strip of glue in order to shear the adhesive. Because the materials which make up the glues exhibit great rigidity or hardness when dry, enormous shearing stresses are required to shear the material over its entire width. These shearing stresses cause great tensile stresses in the wire. As the tensile forces increase, the risk of exceeding the breaking load of the wire increases, which would result in a fractured wire. When the wire is placed along the bead on the inside of the glazing and the wire is pulled from the outside of the vehicle, this risk is particularly great. In this case, the wire is pulled under especially delicate conditions when it passes around the edge of the glass such that there is considerable risk of the wire being broken.
To increase the strength of the wire, an obvious alternative is to increase the wire's diameter. However, such a measure causes drawbacks which prevent obtaining the desired result. Increasing the diameter diminishes the cutting characteristics of the wire. Therefore, increasing the diameter of the wire necessitates exerting greater tensile forces to shear the bead. However, since the forces needed to shear the bead increase faster than the tensile strength of the wire, the use of wire of greater diameter does not solve the existing problem.
Therefore, the objective of the invention is to reduce the tensile forces needed to shear the glue bead, thereby facilitating the removal of the glazing while diminishing the risks of breaking the wire.